1. Field of the invention
The present invention relates to a semiconductor light emitting device in which its cost is reduced, and the light emission efficiency is improved and which is made thin. U.S. patent application 09/221,838 entitled Light Emitting Diode Element and U.S. patent application 09/221,839 entitled Semiconductor Light Emitting Device both naming the inventors Hidekazu Toda and Shinji Isokawa. and both filed on the same day as the present application and incorporated herein by references.
2. Description of the Related Art
Semiconductor light emitting device of the surface mount type using light emitting elements have been used for various industrial and consumer's apparatuses.
An example of such a prior art semiconductor light emitting device will be described with reference to FIG. 1.
The semiconductor light emitting device which is disclosed in Japanese Laid-open Patent Publication No. 9-283803 is also known other than that shown in FIG. 1.
FIG. 1 is a sectional view showing a semiconductor light emitting device 11 using a light emitting diode element (hereinafter abbreviated as LED element) as a semiconductor light emitting element.
In FIG. 1, a reference numeral 1 denotes a rectangular insulating substrate made of an electrically insulating material such as ceramics or non-transparent synthetic resin, which is coated with a pair of metallized wiring layers 2, 3 leading from the bottom of the rectangular insulating substrate 1 to it upper surface via its lateral side thereof. The LED element 6 is formed with a light emitting layer by the vapor phase growth of a nitride compound such as GaN on a sapphire substrate 6a and is formed with p and n side electrodes on one side thereof facing to the rectangular insulating substrate 1.
A reference numeral 7 denotes a reflector which is formed with a cavity 7a for accommodating the LED element 6. The reflector 7 is molded from a substrate of non-transparent synthetic resin to have a predetermined thickness. The cavity 7a is coated on its lateral side with a reflective coating to form a reflective layer. The reflector 7 is laminated on the rectangular insulating substrate 1 with a via bonding layers 9, 10.
Electrically conductive materials 4, 5 are bonded on the surface of respective metallized wiring layers 2, 3. The LED element 6 is die-bonded on the rectangular insulating substrate 1 by using electrically conductive materials 4, 5 as bonding material so that the LED element 6 is accommodated in the cavity 7a of the reflector 7 and the p and n side electrodes on one side 6a of the LED element 6 are electrically connected with a pair of metallized wiring layers 2, 3. A reference numeral 8 denotes a molded portion made of a transparent or semi-transparent synthetic resin, that is a light transmittable synthetic resin molded portion which covers the entire surface of the LED element 6 for sealing it.
The thus formed semiconductor light emitting device 11 comprising the LED element 6 which is die-bonded on the rectangular insulating substrate 1 is surface-mounted on a circuit board. The metallized wiring layers 2, 3 made of an electrically conductive material are connected to wiring conductors formed on the circuit board.
The output light which is emitted from the surface of the sapphire substrate 6b of the semiconductor light emitting element 6 is transmitted through the molded portion 8 and then emitted externally. A part of the output light is reflected on the side of the cavity 7a of the reflector 7. The reflected light is also transmitted through the molded portion 8 is emitted externally so that the light emission efficiency of the semiconductor light emitting device 11 is enhanced.
Since the reflective coating material is applied on the side wall of the cavity which is formed from the substrate of non-transparent synthetic resin to improve the light emitting efficiency in the prior art semiconductor light emitting device in such a manner, there is a problem that man-hour is increased thereby to increase the manufacturing cost. The output light which is emitted in a direction opposite to the light emitting face of the semiconductor light emitting device is considerably lost so that it is not effectively used.
Since the reflector of another member which is formed into a predetermined thickness is laminated on the insulating substrate, the thickness of the reflector may be larger than a necessary thickness even if the thickness of the semiconductor light emitting element is made thinner. This results in that the semiconductor light emitting device has a large elevational size T1.